Most all the gasoline in a city comes from the same source, unless you live in a place with several competing refineries.

They take the raw gasoline and add various additive packages with their coloring agent (different colors for different companies), some like Chevron's Techcron are proven to keep the entire fuel system clean.

If you go to a branded gas station, you get their brand of additives. Some of these run better with certain cars, some cars don't care at all.

Go somewhere else and no telling what you get (they may buy it from the cheapest hauler), as far as extra additives go, but it'll hopefully be rated at least what's on the label -- unless they are scumbag operation, and there are a lot of those even at branded stations.

When I put Costco gas in my SUV, I get worse performance and more knocking then if I put the same octane in it from a 'reputable' (more expensive) gas station.. like say.. BP. It's not watered down, per se, but IMO, it's the gasoline equivalent to a watered down makers and coke.

Considering that one of my cars knows the difference between Chevron and Texaco gasoline--Texaco was the better performer--I have no doubt that what you see at Costco, BJ's, and Sam's Club is not as good. I'm sure it comes down to additives, while the base gasoline is the same.

JFreak:

I'm with you there. it's difficult to comprehend why gasoline is so suddenly more expensive, but it's hardly expensive in contrast to most of the world. Although, your country probably charges as much in taxes as you pay for the gasoline itself.

I use whatever's cheapest or closest and can use 87 octane. My car (2004 Tiburon) doesn't seem to care what gas I put in the tank. I was once driving in the middle of nowhere and the tank was almost empty. Only gas station around was some no-name place I never heard of (I didn't even know what their name was, they had no signs, I didn't find out until I checked my online banking to see the name of the company that charged my card) and my car did fine on that tank of gas. Only time I'll go out of my way to fill up is if I know there's a station nearby that has gas significantly cheaper.

While on the subject, has gas gone up a bit where everyone is? Last night I got word that gas was on its way up, so drove my car across the street to Mobil and filled up at $1.95 and today it was up to well above 2 bucks a gallon

Knock (also called detonation or ping)
Unplanned or premature ignition of the gas-air mixture in the cylinder (that is, ignition that was not initiated by the sparkplug), causes the piston to be forced down when it is in the wrong portion of its stroke, so it interferes with the smooth running of the motor, causing noise, roughness and loss of power. In extreme cases it will damage the motor.

Main causes are gasoline with too low an octane rating, over-compression, ignition timing misadjustment and dirty or damaged pistons/cylinder heads.

It's all in the timing.... think of riding a bicycle, you have to push down on the pedal at the right time, once it has past the top of the curve and is on its way down. If you were to push down on the pedal when it is coming up the rear portion of the cycle, you'll either slow or stop the pedal, or break your leg trying. There is a right time for the force to be applied, if you miss the correct timing, you'll get poor performance.

In this analogy the pedal is the piston, and the push you make is the explosion of the gas/air mixture.

gas stations here in SD all get their gas from the same tanks. the branded tankers line up in front of the same bunch of tanks and then they go to their respective additive nozzles...its just the small amount of additive that makes the branded gas 'different'. it's not a large amount of fuel cleaner either...like the kind that u can buy concentrated in a bottle at the store

gas stations here in SD all get their gas from the same tanks. the branded tankers line up in front of the same bunch of tanks and then they go to their respective additive nozzles...its just the small amount of additive that makes the branded gas 'different'. it's not a large amount of fuel cleaner either...like the kind that u can buy concentrated in a bottle at the store

gas 'difference' is all marketing

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For some people, the color of the gasoline is EXTREMELY important.

Look at how many people refuse to hook up a Dell monitor to their Mac.

All the additives are "supposed" to do the same thing, in practice they basically do. But depending on the history of the vehicle, emissions system, electronics, and the oil. Long term results may vary between the packages and the vehicle may react differently to different additive packages in the short term.

But most all gasoline is more than good enough to basically not gunk up the engine as bad as gasoline from 20 years ago. Valve jobs are rather rare on cars these days.

It depends on the source of Costco's gasoline compared to the others. If it's the same stuff that the mom-and-pop crap gas station uses, then the answer is "No." If it's not substantively different, then "Yes."

One thing to consider: I'm not a Costco customer, but every time I drive by the local Costco it seems like there's a long line out of the gas station pumps. Is it worth the extra time to save that much money? You decide.

I've heard the same theory - that all gas comes from the same pumps. I have a '97 Mercury Van and a '95 Pathfinder that both ping horribly when I buy cheapo gas like wally world. Two mechanics have told me to buy from reputable companies like Shell or Chevron, regardless of what octane I run. I usually try to run a tank of 92 octane every once in awhile.

Costco is at $2.44 today for premium. I can't seem to find out who supplies them with their gas, but I found out that they don't use additives. They do change their pump filters more often than anyone else and conduct octane checks 4 times per year to make sure that the product is good. 2 samples from suppliers trucks and two from their tanks. Not allowing credit cards also helps with the price.

I've been using Costco gas for years and it works great. I tried premium today to see if it would make a difference in a car not specifically rated for it. There wasn't that much of a difference, probably not worth the extra expense. But still better than $2.57 at the nearest Mobil or Chevron.

I've heard the same theory - that all gas comes from the same pumps. I have a '97 Mercury Van and a '95 Pathfinder that both ping horribly when I buy cheapo gas like wally world. Two mechanics have told me to buy from reputable companies like Shell or Chevron, regardless of what octane I run. I usually try to run a tank of 92 octane every once in awhile.

So I don't believe all gas comes from the same pumps...

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I don't think it comes from the same source in most places. In some remote areas, I can see how that could happen if the closest source is the cheapest. Since I've also seen reduced performance from Arco and generic gas brands, I have to believe that there must be some important differences, whether it's the additives or the gasoline.

I'm with you there. it's difficult to comprehend why gasoline is so suddenly more expensive, but it's hardly expensive in contrast to most of the world. Although, your country probably charges as much in taxes as you pay for the gasoline itself.

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In Norway the price is around $6.5 per gallon and we produce and export oil ourselves. How's that for irony?

It depends on the source of Costco's gasoline compared to the others. If it's the same stuff that the mom-and-pop crap gas station uses, then the answer is "No." If it's not substantively different, then "Yes."

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I am not sure I understand your reasoning. My parents used to own a "mom-and-pop CRAP" gas station near Memphis, TN. We sold the same gas as the big named guys. In fact, most of the stations received gas from the same pipeline in Memphis. You guys should do a little more research before you post with nonsense. How many of you have actually had problems with your car that you are SURE was caused by gasoline? Gas is gas folks. Unless it has water in it (if it does, you will know because your car will not run), it is gas. It meets the specs set by the manufactures, and thus is appropriate. The advertising of additives is all MARKETING.

I am not sure I understand your reasoning. My parents used to own a "mom-and-pop CRAP" gas station near Memphis, TN. We sold the same gas as the big named guys. In fact, most of the stations received gas from the same pipeline in Memphis. You guys should do a little more research before you post with nonsense. How many of you have actually had problems with your car that you are SURE was caused by gasoline? Gas is gas folks. Unless it has water in it (if it does, you will know because your car will not run), it is gas. It meets the specs set by the manufactures, and thus is appropriate. The advertising of additives is all MARKETING.

BTW, gas here is $1.90

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By "crap gas station," I meant a gas station that sells crappy gas. For the record, I HAVE seen my vehicle run poorly after filling up at a particular gas station, especially if it's an isolated, non-brand-name, "we're the only gas station for the next 50 miles" gas station. Like I said, if you'd read my post, IF the gas comes from the same place as the big boys, then it doesn't matter. IF it comes from somewhere else, then it does.

I am not sure I understand your reasoning. My parents used to own a "mom-and-pop CRAP" gas station near Memphis, TN. We sold the same gas as the big named guys. In fact, most of the stations received gas from the same pipeline in Memphis. You guys should do a little more research before you post with nonsense. How many of you have actually had problems with your car that you are SURE was caused by gasoline? Gas is gas folks. Unless it has water in it (if it does, you will know because your car will not run), it is gas. It meets the specs set by the manufactures, and thus is appropriate. The advertising of additives is all MARKETING.

BTW, gas here is $1.90

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Sure, gasoline is gasoline, but it would be nice if it all worked the same. You should have mentioned sediment. Why is it that people tell me not to buy gasoline when the tanker is there? It's because sediment builds up at the bottom of the tank and gets stirred up when the tank is being filled. You know that tanks aren't cleaned--they're replaced every couple of years in most states.

Besides that, there are some dealers trying to make some extra money. That happened here in Floriduh after hurricane Charley. Apparently, certain stations added water to make it appear that they had gasoline. It's more difficult to play games these days because of inspectors, but it still happens.

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